Calculate ΔH°rxn in kJ/mol for:
C3H8(g) + 4 CO2(g) + 4 H2(g) → C7H16(g) + 4 O2(g)
from the following given values of ΔH°rxn:
C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(g) ΔH°rxn= -2,010 kJ/mol
C7H16(g) + 11 O2(g) → 7 CO2(g) + 8 H2O(g) ΔH°rxn= -4,426 kJ/mol
H2(g) + ½ O2(g) → H2O(g) ΔH°rxn= -241.8 kJ/mol
The Attempt at a Solution
I swapped the middle to give +4,426 kJ/mol. Then I tried multiplying the middle by 1/2 and the third one by 4. Am I on the right track? Anything else need to be swapped? I feel like the next step should be obvious; I'm just stuck.